Silicon steels, ferrites, amorphous alloys, and Fe-base nano-crystalline alloy materials, or others are known as soft magnetic materials used for reactors for the large current, the choke coils for the active filter, the smoothing choke coils, the various transformers, the parts of the countermeasure of noise such as the magnetic shield material, power supplies for laser, the pulse power magnetic parts for the particle accelerator, or others. However, ferrite materials are generally low in a saturation magnetic flux density, poor in a temperature characteristic, and are not suitable for applications of high power in which a large operation magnetic flux density is needed, from a reason that the ferrites are liable to saturate magnetically. With regard to the silicon steels, they are large in the core losses with respect to the application at a high frequency, although they are not expensive, and have high in the saturation magnetic flux densities. In the case of Fe-base amorphous alloys, problems are posed that they have large magnetostriction and their characteristics are deteriorated resulting from stresses they undergo, and that they generate large noises in the applications such as a case where currents of an audible frequency band are superposed. On the other hand, in Co-base amorphous alloys, there are problems that its practical material has a low saturation magnetic flux density so as to have not more than 1 T (tesla), and is thermally unstable. Therefore, when the Co-base amorphous alloys are used for the application of high power, there cause problems that size of magnetic parts made of the alloy become large and that the core losses of them are increased because of aged deterioration.
Since Fe-base nano-crystalline alloys show excellent soft magnetic properties, it is used for magnetic cores of such as the common mode choke coils, high frequency transformers, pulse transformers, and others. As a representative composition, Fe—Cu—(Nb, Ti, Zr, Hf, Mo, W, Ta)—Si—B alloys, Fe—Cu—(Nb, Ti, Zr, Hf, Mo, W, Ta)—B alloys, or others disclosed in U.S. Pat. No. 4,881,989 or JP-A-01-242755 is known. These Fe-base nano-crystalline alloys are produced after amorphous alloys of them were formed by being rapidly quenched from generally their liquid phases or vapor phases, and then are finely crystallized by a heat treatment. As methods of quenching from the liquid phase, there are known a single roll method, a double roll method, a centrifugal quenching method, a rotating liquid spinning method, an atomization method, a cavitation method, and others. In addition, the methods of quenching from the vapor phase, there are known a sputtering method, a vapor deposition method, an ion plating method, and others are known. The Fe-base nano-crystalline alloys are produced after the amorphous alloys of them were produced by the above mentioned methods, and then are finely crystallized into the products which hardly show thermal instability as viewed in the amorphous alloys, and are known to show the high saturation magnetic flux densities the same degrees as those of the Fe-base amorphous alloys, low magnetostriction, and the excellent soft magnetic properties. Furthermore, the nano-crystalline alloys are known to be small in the aged deterioration, and also to be excellent in the temperature characteristics.
Further, addition of Co to the Fe-base nano-crystalline alloy is also investigated, and JP-A-09-20965 discloses that a range of an excellent ratio of a Co amount is not more than 0.2.
Furthermore, as Co-base nano-crystalline alloys, alloys disclosed in U.S. Pat. No. 5,151,137 are known. However, it is difficult to realize the high saturation magnetic flux density and the low core loss in these alloys.
When compared with materials of a related art having substantially the same saturation magnetic flux density, an Fe-base nano-crystalline soft magnetic alloy is high in permeability, and are low in the core loss, thus is excellent in the soft magnetic property. However, in the Fe—Cu—Nb—Si—B alloy corresponding to a representative nano-crystalline soft magnetic alloy, it is difficult to realize the low core loss in a condition where the saturation magnetic flux density exceeds 1.65 T. Furthermore, even when Co is added, a remarkable increase of the saturation magnetic flux density cannot be confirmed.
On the other hand, in an Fe—Zr—B alloy or an Fe—Nb—B alloy, materials increasing the saturation magnetic flux densities to not less than 1.65 T become hard to form, and it is difficult to produce the materials in large amount. Furthermore, the materials have drawbacks that they are poor in the temperature characteristics because their core losses increase rapidly in association with the elevation in temperature. Although such drawbacks that the materials are poor in the temperature characteristics are dissolved and features of high saturation magnetic flux densities are included in them through the addition of Co, these alloys which are heat treated in a non-magnetic field have a problem that their core losses are remarkably large compared with Fe-base materials having no addition of Co. Therefore, these alloys are difficult to be used for the various magnetic parts described above. Furthermore, these alloys have a problem in terms of a short life of nozzle, because reactivity of the alloys with the nozzle is enhanced in the case of producing them in the large amount.